What is a SIC code?

By DormantFile · Updated 28 March 2026

A SIC code (Standard Industrial Classification code) is a 5-digit number that describes what your company does. Companies House uses SIC codes to categorise every company on the register by industry and activity.

Where SIC codes come from

The UK uses the SIC 2007 system, which contains hundreds of codes covering everything from wheat farming (01110) to management consultancy (70229). You choose at least one SIC code when you incorporate a company, and it appears on the public register.

Which SIC code do dormant companies use?

If your company is dormant, the correct SIC code is:

99999 — Dormant company — no significant trading activity

This tells anyone searching the register that the company exists but is not actively trading. Most dormant companies should have this code. If your company was previously active and has since become dormant, you should update the SIC code to 99999 to reflect the change.

How to find your SIC code

You can look up your company's current SIC code on the Companies House register. Search for your company name or number and the SIC code will appear in the company overview.

How to change your SIC code

You update your SIC code by filing a confirmation statement (CS01) with Companies House. The confirmation statement includes a section where you can add, remove, or change your SIC codes. There is no separate form — it is handled as part of the CS01 process.

You can change your SIC code at any time by filing an early confirmation statement, though most directors update it at the next scheduled filing.

Why it matters

Using the correct SIC code is not just a formality. It ensures your company appears accurately on the public register and can affect things like insurance quotes and credit checks. For dormant companies, 99999 makes your status immediately clear to anyone reviewing the filing.

Read the full guide: First year filing for a new dormant company